This invention relates to medical equipment and, more particularly, to a valve that controls a respirator.
My copending application Ser. No. 936,380, filed Aug. 24, 1978, discloses a sensitive bipolar flowmeter for measuring the gas flow rate between a respirator and a patient. One type of respirator comprises a bellows that is expanded and contracted to control gas flow to the patient. The volume change of the bellows and the volume of gas received by the patient are not accurately related. Control valves are not commonly used in a regulator because the seals and rubbing parts of such valves are subject to wear and thus require frequent maintenance. The inertia of moving parts also increases the response time when functioning in an automatic control system. In addition, contamination of the gas supplied to the patient by the lubricant for the rubbing parts of the valve is a danger.